Explosive tools for driving studs



B. J. ELLIOTT EXPLOSIVE TOOLS FOR DRIVING STUDS Filed Aug. 11. 1961INVENTOR ERNARD JESSE ELLIOT T Dec. 31, 1963 United States Patent O3,115,636 EXPLSIVE TGLS FOR DRIVING STUDS Bernard .lesse Elliott,Clifton Hill, Victoria, Australia, assigner to Olin Mathieson ChemicalCorporation, a corporation of Virginia Filed Aug. 11, 1961, Ser. No.130,938 7 Claims. (Cl. 1-44.5)

This invention relates to explosive actuated tools for driving studs orother fastener elements into walls or other solid surfaces, and morespecifically it refers to tools of the kind in which the explosivecartridge is exploded by means of a hammer blow applied to the upper endof a striker member and the driving force of the explosive istransmitted to the fastener element through the intermediary of apiston-like member slidable in the barrel of the tool.

With such tools, it is necessary to provide safety means for locking orholding the striker member to prevent accidental tiring in the event ofthe tool being dropped or otherwise mishandled. The present inventionhas for its object to improve upon such safety means whereby they arerendered generally more eicient and less liable to damage and excessivewear in use.

According to the invention, there is provided in a fastener driving toolof the type described, safety means for locking or holding the strikermember comprising rollers in engagement with an internal sloped surfaceand in linear engagement with the curved surface of the shank of thestriker member, the rollers functioning with a wedging action to gripthe shank of the striker member and the linear contact distributing thegripping pressure along the line of contact with said shank. Y Withtools of this kind accidents are possible if the tool should, throughcarelessness or mistake, be used on walls or surfaces not suicientlysolid to hold the fastener. Thus, if the tool should be used onbreboard, fibroplaster, plywood or veneered walls, it is possible forthe fastener to completely penetrate the wall and continue in freeflight, in which case it may strike a workman or ricochet in anotherdirection.

There is provided in a fastener driving tool of the above type, thecombination of means for positively connecting the fastener element tothe piston-like member prior to firing, and means for arresting thepiston-like member in the event of over travel so that the fastenerelement is automatically arrested should the tool be used on a wall orsurface not sufficiently solid to hold the fastener element.

The invention is more fully described aided by reference to theaccompanying drawings wherein:

FIG. l is a longitudinal sectional view of a fastener driving toolaccording to the invention, the safety means being in position to lockor hold the striker member.

FIG. 2 is a similar View to FIG. l, but showing the safety means inreleased position.

FIG. 3 is a detail View of one of the rollers.

FIG. 4 is a detail View of the roller cage.

As is shownvin these views, the tool comprises a substantiallycylindrical barrel 1 within the bore of which are slidably arranged thestriker member 2 and the pistonlike member 3. At the upper end, thebarrel supports a bearing member 4 through which the shank of thestriker member slidably passes.

The bearing member encloses a cage 5 having gaps 6 housing the rollers7. The cage 5 is acted on by a spring 8 pressing at its lower end on awasher 9 which seats on the top of the cage and also functions to holdthe rollers in position in the gaps 6. The upper end of the spring seatsagainst a cap 10 inserted into the upper end of the bearing member andheld in position by means such as a C-shaped split snap ring il.

The rollers bear against an internal sloped surface 12 on the bearingmember 4 and also against the shank of the striker member 2. They arepreferably of the shape shown in FIG. 3, each having a central concavecurved surface 13 to Contact with the curved surface of the Shank of thestriker member and two end convex curved surfaces 14 to bear against theinternal sloped surface 12 which is also curved. The curvature of thesurfaces 13 and 14 is such that they closely contact with the shank ofthe striker member and the internal sloped surface 12 of the bearingmember.

The construction of the rollers as above described provides a veryeiective locking grip on the shank of the striker member as the rollersare forced into wedging engagement with the internal sloped surface 12by the spring 8 and linear contact is established over the wholecontacting surface. The linear contact of the rollers also reducesdamage by scoring and excessive wear on the surface of the shank of thestriker member and the sloped internal wall 12 because the pressure isdistributed along the line of contact instead of being concentrated atone point as would be the case if balls were used.

The bearing member 4 has holes 15 accommodating release balls 16 capableof engaging the lower end of the cage 5 to move the cage upwardly andrelease the gripping engagement of the rollers 7 with the striker membershank. The release balls 16 are forced against the lower end of the cageby means of the internal faces of a sleeve 17 slidably encircling theupper portion of the barrel and spring-pressed by a coiled spring 18normally to the position in which internal gaps 19 in said sleeveregister with the release balls. The release balls are thus free and thespring-pressed rollers 7 grip the striker member shank with a wedgingaction. Said rollers are released prior to firing by moving the sleeve17 forwardly against the spring 1S so that the internal gaps 19 movepast the release balls 16 and said release balls are thus forcedinwardly by the internal faces of the sleeve to engage the lower end ofthe cage 5 and, by forcing said cage upwardly, release the rollers fromwedging engagement with the shank of the striker member 2. Said strikermember can then be driven downwardly by a hammer blow.

The piston-like member 3 may be constructed as having a longitudinallyarranged cavity 20 in its upper end to receive the cartridge, the latterpreferably being of the rim fire type. The cartridge is supported bysaid cavity longitudinally in relation to the piston-like member andwith its rim uppermost. Said cavity is preferably arranged eccentricallyof the axis of the piston-like member and is opened laterally by a slot21 to the outer periphery of the piston-like member to enable a suitabletool to be inserted for ejecting the spent cartridge. The lateral slotis of less width than the diameter of the cavity and is arranged at theportion of reduced thickness resulting from the eccentric arrangement ofthe cavity.

The cartridge, when inserted, has its rim standing clear of the upperend of the cavity and is exploded by the contact of the lower end of thestriker member 2 with the cartridge when said striker member is struckby a hammer or the like following release of safety shank gripping meansabove described.

The piston-like member 3 is withdrawable for loading purposes fromthelower or muzzle end of the barrel and the fastener element is screwed orotherwise attached t0 the lower end of the piston-like member so that itcannot penetrate completely through the wall or surface into which it isiired and' enter into free Hight.

The lower end of the barrel 1 is provided with safety means to arrestthe movement of the piston-like member. Said means may comprise balls 22mounted in cavities 23 in the side of the barre-l and normally held inprotrud- Patented Dec. 31, 1963` ing position to ar-res-t thepiston-like member by means of a spring-pressed sleeve 2dencircling thebarrel at its lower end. The sleeve has gaps so that, when it isslidably moved rearwardly by Ihand lagainst spring 18, i.e. moved inFIGS. 1 and Z upwardly, the balls 22 are released, enabling thepiston-like member 3 to be withdrawn from the lower or muzzle end of thebarrel for ejection of the spent cartridge and re-loading.

The pistonalike member 3 has a lower reduced portion 26 against whichthe balls 22 normally do not engage and an upper portion 27 of normalbarrel bore engaging diameter providing a shoulder between portions 26and 27 which engages the balls when the piston-like member is beingarrested.

For safety purposes, further balls 28 may be provided intermediate thegroup of balls 16 and the group of balls 22 as arresting means above thepiston-like member 3 to prevent the striker member 2t from being drivendownwardly until such time as the piston-like member is inserted andcorrectly positioned. The latter balls are also pressed into position bythe sleeve 24, the latter having clearance gaps 29* for such safetyballs. The arrangement is such that, when the sleeve 24 is in positionto release the llower balls 22 to permit withdrawal yof the pistonlikemember, the upper balls 23 protrude into the barrel to give protectionagainst the striker member and, when the sleeve is in position to causethe lower balls 22 t protrude into the barrel to function as safetyarresting means for the piston-like member, the upper balls 28 arereleased.

The two sleeves @17 and 24 may be acted `upon by the same coiled spring`18 and may slide one within the other.

Normally, when |the tool is used on a wall or surface of sufficientsolidity to hold the fastener element, the fastener element in itspenetration of the wall arrests the piston-like member 3 before theupper normal diameter por-tion 27 of the piston-like member engages theballs 22. lf, however, the tool should, through carelessness or error,be used on a wall or surface not sufficiently solid to hold the fastenerelement, the piston-like member 3 over travels until the shoulder 30engages the balls 22 and it is thereby automatically arrested. Since thefastener `element is positively connected to the piston-like member 3 bythe screwthreaded engagement, the fastener element is likewise arrested.Thus, it is impossible for the fastener element to penetrate into thewall beyond a predetermined distance even in soft or thin wall surfaces,and can never completely penetrate the wall and enter into free ilightbeyond the wall.

What is claimed is:

l. In a fastener driving tool of the type having a barrel member with anaxially extending bore, a charge of explosive in said bore, an explosiveactuated pistonA member carried slideably with a work surface impactingfastener and said explosive in said bore -for axial movement relative tosaid barrel member to drive said fastener, a striker member carriedslideably in said bore and having a shank with a cylindrical surfaceaxially extending into said barrel bore, an impact receiving end andmeans at the opposite end for tiring said explosive carried in said borebetween said members by movement of said striker member relative to saidpiston member` yunder an impact on said receiving end, and safety meansfor preventing accidental ring comprising a bearing member having aninternal sloped surface axially converging in said -one direction andmounted ron the rearward end of said barrel member idetachiably forslideably receiving said shank and `disposing said sloped surface inaxial alignment with said bore, and rollers in linear engagement withsaid internal sloped surface and with said cylindrical surface of saidshank transversely of said bore, a cage between said surface and shank,and a spring acting forwardly on said cage normally pressing the rollersinto wedging engagement between said surface and shank, said cage havingcircumferentially spaced `gaps wherein the rollers are housed, saidspring presesd rollers and surfaces normally providing by saidengagement a wedging action relative to said striker and barrel membersto grip said striker member against movement in said one direction, andsaid linear engagement distributing all the pressure of said grip alonga line of contact extending at least partly about the cylindricalsurface, and axially movable means mounted on said barrel member formanual actuation to move said rollers out of said engagement and therebyrelease said safety means to permit movement of said striker member insaid -one direction.

2. The tool fof claim 1 wherein the axially movable means includes arelease sleeve with an internally projecting face and a gap and' alsorelease balls carried between the bearing member and said sleeve forengagement of said balls with the front of the cage under the inwardpress of said face whereby said cage and rollers are forced rearwardlyto release the wedging engagement between the rollers, shank, andbearing member, said sleeve being slideably mounted in encirclingrelationship with the bar- -rel and said bearing member, means normallypressing said sleeve to a position in which said gap registers wi-th therelease balls, allowing them to move outwardly and the cage yand rollersforwardly to establish said wedging engagement under the impetus of theforwardly acting spring of the bearing member.

3. The fastener driving tool of claim l wherein the internal slopedsurface is circumferentially curved and the rollers each have a centralconcave curved surface to contact with the curved surface of the shankof the striker member and two end convex curved surfaces to bear againstthe internal sloped surface.

4. The :fastener fdriving tool as claimed in claim 1 wherein the springat its forward end presses on a washer seated on the rear of the cage,said spring and washer functioning to hold the rollers in position inthe gaps of the cage.

5. In a fas-tener driving tool of the type having an openended barrelwith a bore extending axially between a breech opening and a muzzleopening the combination of a fastener-driving piston member receivedtogether with la wo-rk surface impacting fastener for axial movemen-t insaid bore, said piston member being adapted unider explosive actuationin said bore to drive said fastener in one direction of said movement, astriker member insertable in said barrel at said breech opening, acharge of explosive received in said barrel, said members beingslideably movable in said bore relative to each other and said explosivedisposed within said bore at a location therein between said members,said striker member having one end adapted to receive an impact forfiring said explosive by contact with said members being moved togetherat said location and in said [direction when said one end is impactedwhile said fastener is impacted against said surface; means forpreventing accidental movement of said striker member in said onedirection comprising an internal barrel surface sloped with axialconvergence in said one direction, rolling members mounted between saidbarrel surface and striker member normally urged into wedging engagementin said one direction to grip said striker member against movement insaid direction, and axially movable release means including a sleevemember and a cage mounted between said barrel and striker member fforactuation to move said rolling members in the opposite direction 'out ofsaid engagement permitting movement of said striker member in said onedirection; means positivelyl connecting said fastener to said pistonmember prior to tiring; releasable detent means for arresting saidpiston member against travel in said direction out yof said location;and control means mounted on said barrel for movement between oneposition at which said release means is moved in said opposite directionand said striker is free to extend in said one direction to saidlocation to re said explosive, and whereat .said detent means arreststhe piston member and fastener against overtravel out of said location,and another position at which the ldetent means ils released to allowremoval of said piston member from said muzzle opening and whereat therelease means is unactulalted and the movement of said striker member isprevented in said one direction.

6. The tool of claim 5 wherein the piston member has a reduced `frontportion with an internally sorew threaded socket providing a positiveconnecting means ywith a screw threaded end of fthe fastener, and has arear portion of enlarged -idiameter normally fitting the barrel bore,said portions delininlg a shoulder engageable with the detent means.

7. The tool of claim 5 lwherein the release means includes -a rear groupof radially movable balls, the detent means includes a front group ofradially movable balls, wherein the control means includes axiallymovable first and second sleeves supported with both said groups on thebarrel, each said sleeve h-aving an intennal protrusion al-ignable withsaid balls for pressing said balls inwardly and having axially spacedfrom said sleeve protrusion an internal gap alignable with said ballsfor allowing the balls to move outwardly, and rneans biasing saidsleeves to align the internal gap of said first sleeve normally withsaid rear group and to align the internal protmsion of said secondsleeve normally with said front group, and wherein the tool incluldesintermediate larresting means carried by the barrel and operable by saidsecond sleeve in alltemation with the detent means to extend saidintermediate means into said barrel between :said striker member and thepiston member passed by said released detent means for removal.

References Cited in the lile of this patent FOREIGN PATENTS 1,221,131France May 31, 1960

1. IN A FASTENER DRIVING TOOL OF THE TYPE HAVING A BARREL MEMBER WITH ANAXIALLY EXTENDING BORE, A CHARGE OF EXPLOSIVE IN SAID BORE, AN EXPLOSIVEACTUATED PISTON MEMBER CARRIED SLIDEABLY WITH A WORK SURFACE IMPACTINGFASTENER AND SAID EXPLOSIVE IN SAID BORE FOR AXIAL MOVEMENT RELATIVE TOSAID BARREL MEMBER TO DRIVE SAID FASTENER, A STRIKER MEMBER CARRIEDSLIDEABLY IN SAID BORE AND HAVING A SHANK WITH A CYLINDRICAL SURFACEAXIALLY EXTENDING INTO SAID BARREL BORE, AN IMPACT RECEIVING END ANDMEANS AT THE OPPOSITE END FOR FIRING SAID EXPLOSIVE CARRIED IN SAID BOREBETWEEN SAID MEMBERS BY MOVEMENT OF SAID STRIKER MEMBER RELATIVE TO SAIDPISTON MEMBER UNDER AN IMPACT ON SAID RECEIVING END, AND SAFETY MEANSFOR PREVENTING ACCIDENTAL FIRING COMPRISING A BEARING MEMBER HAVING ANINTERNAL SLOPED SURFACE AXIALLY CONVERGING IN SAID ONE DIRECTION ANDMOUNTED ON THE REARWARD END OF SAID BARREL MEMBER DETACHABLY FORSLIDEABLY RECEIVING SAID SHANK AND DISPOSING SAID SLOPED SURFACE INAXIAL ALIGNMENT WITH SAID BORE, AND ROLLERS IN LINEAR ENGAGEMENT WITHSAID INTERNAL SLOPED SURFACE AND WITH SAID CYLINDRICAL SURFACE OF SAIDSHANK TRANVERSELY OF SAID BORE, A CAGE BETWEEN SAID SURFACE AND SHANK,AND A SPRING ACTING FORWARDLY ON SAID CAGE NORMALLY PRESSING THE ROLLERSINTO WEDGING ENGAGEMENT BETWEEN SAID SURFACE AND SHANK, SAID CAGE HAVINGCIRCUMFERENTIALLY SPACED GAPS WHEREIN THE ROLLERS ARE HOUSED, SAIDSPRING PRESSED ROLLERS AND SURFACES NORMALLY PROVIDING BY SAIDENGAGEMENT A WEDGING ACTION RELATIVE TO SAID STRIKER AND BARREL MEMBERSTO GRIP SAID STRIKER MEMBER AGAINST MOVEMENT IN SAID ONE DIRECTION, ANDSAID LINEAR ENGAGEMENT DISTRIBUTING ALL THE PRESSURE OF SAID GRIP ALONGA LINE OF CONTACT EXTENDING AT LEAST PARTLY ABOUT THE CYLINDRICALSURFACE, AND AXIALLY MOVABLE MEANS MOUNTED ON SAID BARREL MEMBER FORMANUAL ACTUATION TO MOVE SAID ROLLERS OUT OF SAID ENGAGEMENT AND THEREBYRELEASE SAID SAFETY MEANS TO PERMIT MOVEMENT OF SAID STRIKER MEMBER INSAID ONE DIRECTION.